Time switch



Se t. 14, 1954 s. w. SCHROEDER TIME SWITCH 2 Sheets-Sheet 1 Filed Nov. 12, 1953 INVENTOR.

GEORGE W. SCHROEDER HIS ATTORNEY Patented Sept. 14, 1954 TIME SWITCH George W.Schroeder, Louisville, Ky.,' assigncr to General Electric Company, a corporation of New York Application November 12, 1953, Serial No. 391,438

My invention relates to improvements in time switches and in particular to an improved time switch especially useful for the control of electric range ovens and the like.

Many time switches or timers heretofore generally used for the control of electric range ovens have the disadvantage that the housewife, when setting the timer, must manipulate three separate control knobs to set the desired times at which the oven will be turned on and "off and to cook the timer for automatic operation. Furthermore although separate control knobs are provided it is usually necessary to make the various settings in a particular sequence to effect proper operation of the timer.

Another disadvantage of such prior art range timers is that in addition to the usual clock dial two separate dials are provided for indicating the on and off times during a timed cooking operation, thus adding to the complexity of the device. Also in some timers the off time is set by setting a rotatable dial on the clock face with respect to the hour hand and thus the numerals on this dial may be upside down or in various angular positions when the setting is made. Finally the on dial is frequently calibrated in terms of hours to cook, necessitating mental calculations to determine exactly when the cooking operation will begin.

Accordingly, a principal object of this invention is to overcome the aforementioned disadvantages and diinculties by providing an improved time switch having a single control knob for cocking the switch and setting the on and off times at which the switch contacts are closed and opened.

Another object of this invention is to provide a time switch so arranged that the on and off times are indicated by rotatable time indicators cooperating with a conventional clock dial.

Another object of my invention is to provide a time switch including a single control knob for cocking the switch and setting the on and off times and which also includes on and off time indicators cooperating with a conventional clock dial together with a dial and indicator for indicating the interval between the on and off times.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly stated, in accordance with one aspect of 5 Claims. (Cl. 161-1) my invention an axially movable pin is provided in telescoping alignment with a rotatable and axially movable shaft. The desired switching operations are effected by the respective axial motions of the pin and the shaft, as hereinafter explained. The shaft includes a lug member which cooperates with a manually rotatable plate in such a manner that the respective axial motions of the pin and shaft take place in accord ance with the relative angular positions of the shaft and the plate. A rotatable tripping member driven by a suitable clock or timing mechanism releases the pin for axial motion when in predetermined angular relation to the shaft, and then drives the shaft to another predetermined angular position with respect to the rotatable plate Where it in turn is released for axial motion. The desired on and off time settings are made by adjusting the initial relative angular positions of the shaft and the rotatable plate. Cocking is automatically effected by rota- .tion of the parts while setting the desired cooking Fig. 3 is a top plan view of the same range timer, but with some of the parts removed or broken away.

Fig. 4 is a sectional view taken along the line 4-4 of Fig. 2, and shows the parts as they appear during a timed cooking operation.

Fig. 5 is similar to Fig. 4 but shows the parts as they appear after a timed cooking operation has been completed.

Fig. 6 is similar to Fig. 4 but shows the parts as they appear after the timer has been set and cooked, but before the timed cooking operation has begun.

Fig. '7 is a rear elevation view Of the same timer, some of the parts being removed or broken away.

Fig. 8 is a detail view taken generally along the line 8-8 of Fig. 3, some of the parts being removed or broken away.

. Fig. 9 is a detail view of parts of the mechanism shown in Fig. 8.

Referring now to the drawings, the timer may be mounted in any suitable manner, preferably upon the backsplash l of an electric range. It m y include clock means for indicating the time of day, which as illustrated comprises a numbered clock bezel 2, a minute hand 3 and an hour hand 4. The minute and hour hands are of course rotated by a conventional clock mechanism, and if desired the hands and the clock face may be protected by a glass cover in the usual manner. For setting the clock, there may be provided a knob 5 which extends through the glass cover, and is attached to a shaft which carries minute hand 3; the clock may be set by rotating knob 5 in the conventional manner.

Preferably the timer includes manually rotatable time indicator means cooperating with clock bezel 2 for indicating the times at which a cooking operation is to begin and end. For indicating the time at which a cooking operation is to begin I provide a rotatable time indicator in the form of a disk 6 coaxial with the shaft on which minute hand 3 is mounted. Disk 6 includes an arrow or pointer I painted on the surface thereof so as to cooperate with the numerals on clock bezel 2. A second pointer 8 may also be painted on ,disk 6 for the purpose of providing an indication of the time interval between the beginning and end of the cooking operation, as hereinafter more fully explained. Disk 6 is mounted for rotation in either direction and may be manually rotated and set by setting means including a control knob 9. As knob 9 is turned clockwise disk 6 is also turned clockwise and the angular relation between pointer I on disk 5 and clock bezel 2 may be adjusted to any desired setting. As more fully explained hereinafter the angular position of pointer I with respect to clock bezel 2 determines the time at which the switch contacts of the range timer are closed to energize the heating units in the range oven and thus initiate the cooking operation.

In accordance with my invention a second rotatable time indicator in the form of a disk l0 having an outwardly projecting sector shaped portion H is arranged to cooperate with clock bezel 2 to indicate the time at which the oven is to be turned off, and also, if desired, to cooperate with disk 6 to indicate the time interval between the beginning and the end of the cooking operation. A pointer I2 is painted on sector portion ll of disk l0 so as to cooperate with the numerals on clock bezel 2 to indicate the time at which the oven is to be turned off, and also numerals from 0 to 7, for example, are painted adjacent the periphery of disk In at spaced intervals so as to cooperate with pointer 8 on disk 6 in indicating the hours to cook or time interval between the beginning and end of the cooking operation. As explained more fully hereinafter disk I!) is rotatable in the clockwise direction only, the gear train with which it is associated having means for preventing counterclockwise rotation.

An important feature of my improved timer is that the positions of both pointer I carried by disk 6 and pointer l2 carried by disk l0 may be set by means of control knob 9. Both disks are provided with separate gear trains which however may be interconnected by clockwise rotation of knob 9 during the initial step of the setting operation. In the operation of the timer, clockwise rotation of knob 9 causes disks 6 and H] to rotate clockwise in fixed angular relationship to each other, while counterclockwise rotation of knob 9 results in counterclockwise rotation of disk 6 alone.

For example, it will be assumed that the time of day is nine oclock as shown in Fig. 2, and

that the housewife desires to cook food in the oven for a period of two hours and have the cooking completed at six oclock. To set the timer for this operation, she turns knob 9 clockwise until pointer l2 carried by disk I0 points to the numeral 6 on clock bezel 2, and then turns knob counterclockwise until pointer I carried by disk 6 points to the numeral 4 on clock bezel 2. The timer will then appear as shown in Fig. 1 of the drawing it being noted that pointer 8 on disk 6 points to the numeral 2 on disk It thus indicating that the duration of the cooking ope-ration is to be two hours. It is evident that once the housewife has set the time at which the cooking operation is to be completed she may then set pointer 8 to the desired number of hours to cook or she may set the time at which the cooking operation is to begin by observing the position of pointer I with respect to clock bezel 2.

In the assumed example the oven will remain oil until four oclock at which time the switch contacts of the timer will be automatically closed and rotation of disk 6 at the rate of one revolution every twelve hours will begin. During the .two hour cooking period pointer B will continuously indicate the time remaining before the operation is completed and pointer I will coincide with hour hand 4 and rotate in fixed angular relationship therewith. At six oclock the switch contacts will be opened, pointer I will disappear under and be hidden by sector portion I of disk I, and the gear trains associated with disks 6 and II) will be disengaged from each other and from the clock mechanism.

Referring now to Figs. 2 and 3, the clock mechanism may comprise a small synchronous electric motor l3 which operates through suitable gearing as shown to turn the gear M at a fixed speed of one revolution per hour. Gear I4 is rotatable about shaft I5 and is connected thereto by conventional friction clutch means I6. The minute hand 3 and the clock setting knob 5 are connected to shaft i5, and thus the synchronous motor l3 rotates the minute hand 3 at a speed of one revolution per hour in the conventional manner. The clock may be set by turning knob 5 with sufiicient force to cause friction clutch means l6 to slip in the usual way. The hour hand 4 is attached to a shaft l1 (see Fig. 8) which is geared to shaft l5 through gear lfl, pinion |9 and gear 20, so that shaft II and hence hour hand 4 and gear I8 are rotated at a fixed speed or one revolution each twelve hours. Shafts l5 and II are rotatably supported by an arbor 2| staked to a supporting plate 22. It will be appreciated that this clock mechanism is largely conventional, and that other clock mechanisms such as a spring driven clock may be employed without altering the principles of my invention.

Gear 23 to which disk 6 is fixedly secured is also mounted for rotation about arbor 2|; likewise, gear 24 and disk I0 are fixedly secured to a common shaft concentrically supported on .1 arbor 2| so as to permit independent rotation of these parts with respect to the other members supported on the arbor. Gear 23 and disk 6 may be rotated in either direction by control knob 9 inasmuch as gear 23 is connected by means of gears 25 and 26 to shaft 26a on which control knob 9 is attached.

Referring now to Figs. 6 and 8 of the drawing gear I8 engages a rotatable tripping gear 21 having an car 28 extending from one of its sides as shown. As gear I8 rotates it rotates gear 21 to maintain at all times a fixed angular relation between hour hand 4 and car 28. For convenience the direction in which the parts are rotated by the clock mechanism will be referred to herein as "the forward direction and the opposite direction of rotation will be referred to as the reverse direction. It will be noted that the forward direction of rotation for gear I8 is clockwise while the forward direction of rotation for gear 21 is counterclockwise.

Coaxial with' gear 21 is a rotatable and axially movable shaft 29 having an axial bore 30 and a diametrical' slot 3| extending transversely to the inner portion of bore 30. A lug 32 is attached to shaft 29 by a nut 33 and is held in fixed angular relation to the shaft by suitable means such as a key on the lug and a keyway in the shaft (not shown). Lug 32 cooperates with a rotatable plate or gear 34 having an arcuate opening 35 which lug 32 may enter when lug 32 and plate 34 are in predetermined angular positions, as hereinafter explained.

An outwardly extending arm 35 attached to shaft 29 carries a pivot 31 which is parallel and rotates with the shaft. A latching lever 33 rotatably supported by pivot 31 extends generally outward from shaft 29 and rotates with the shaft. As best shown in Fig. 9, a slight clockwise rotation of lever 38 about pivot 3! forces the inner end of lever 38 into slot 3|, while a slight counterclockwise rotation of lever 33 about pivot 3'! withdraws the inner end of the lever at least partially out of the slot 3| for purposes hereinafter explained.

Mounted in axial alignment with shaft 29 is a shaft 39 onwhich a gear 40 is fixedly secured. Referring to Fig. 3 it will be obseved that gear 33 meshes with gear 23 and thus that gear 43 may be rotated by control knob 8 in fixed angular relationship with respect to disk 3. Also attached to shaft 39 is a dog 4| which engages the outer portion of lever 38 so that clockwise rotation of shaft 39 causes dog 4| to press against the outer portion of lever 48 thus forcing the inner portion of lever 33 into slot 3i and thereafter producing clockwise rotation of shaft 23. As shown in Fig. 4 pivot 31 passes through a small generally arcuate opening 42 of dog 4! so that shafts 2i! and 39 rotate substantially together, but with suflicient backlash provided by movemerit of pivot 3] in slot 42 to permit the slight rotation of lever 38 about pivot 37 necessary to permit the inner end of lever 33 to move in or partially out of slot 3| selectively. A spring member 43 may connect gear 43 with pivot 3'2 as shown in Fig. 2 so that the spring tends to press the inner end of lever 33 to a position fully within slot 3 I.

A pin 44 is axially slidable in bore 33 and in telescoping axial alignment with shaft 23. When the inner end of lever 38 is fully within the slot 3|, lever 38 interferes with axial motion of pin 44 in relation to shaft 23 as hereinafter explained. This Will be referred to as the latching position of lever 38, since pin 44 is latched against axial motion. When the lower end of lever 38 is partially withdrawn from slot 3|, pin 4*: is freed for axial motion. This will be referred to as the unlatching position of lever 3t. Pin 44 is attached to a yoke 45 which cooperates with plate 34 to limit axial motion of pin 44; as hereinafter explained this axial motion of pin M closes the switch contacts to turn the oven on.

Referring to Figs. 3, '7 and 8, rotatable plate or gear 34 is connected for rotation with gear 24 and disk ID in a predetermined constant angular relationship therewith. The gear train connecting rotatable plate 34 and gear 24 includes pinion 46 in mesh with the teeth on the periphery of plate 34, and the gears 41 and 48 fixedly secured to shaft llii which engage pinion 46 and the gear 24 respectively. The gear train connecting rotatable plate 33 and gear 2d includes means for preventing rotation in the reverse direction (i. e. counterclockwise rotation of gear 24) which as shown in Fig. 8 may include a ratchet device fixedly secured to shaft 43 and arranged to cooperate with a plurality of small slots arranged in a circular pattern in plate 22. A plurality of resilient fingers on the periphery of ratchet device 53 cooperate with the aforementioned slots to prevent reverse rotation of gear .8 and the other gear members engaged therewith. From the foregoing description it is evi" dent that disk i i) which is fixedly associated with gear 2i is rotated clockwise when rotatable plate 34 is rotated in the forward direction. Also it will be recalled that the function of disk ill is to indicate by means of pointer |2 the time at which the oven is to be turned off, and that in setting the timer the housewife first rotates knob 9 clockwise to make this setting. As previously described lug 32 is rotated in the forward direction by clockwise rotation of knob 3 and is arranged to engage arcuate opening 33 in plate 34 when the lug and opening are aligned as shown in Fig. 5. When the lug 32. and rotatable plate 34 are engaged in this manner clockwise rotation of knob 55 effects rotation of plate 34 and disk H1 in the forward direction, and hence the off time may be set by means of knob 3. After this setting is made counterclockwise rotation of knob 9 has no effect on the positions of plate 34 or disk in inasmuch as these members are locked against reverse rotation by ratchet means 53; however counterclockwise rotation of knob 9 does produce rotation of log 32 and disk 3 in the reverse direction because the sloping cam surface of lug 32 permits its withdrawal from opening 35.

Referring now to Figs. 4 and 7, an electrically non-conducting terminal strip 5| is secured to the frame of the timer by means of screw 35!, for example. Attached to the terminal strip are two sets of electrical connectors 53 and i l and two sets of resiliently flexible metal leaves 55 and 5G. Leaves 55 and 56 are attached at one end to the terminal strip 5! and extend generally downward therefrom as shown, and are elsetrically connected to connectors 53 and 5d respectively. The free ends of leaves 55 and {it are provided with electrical contacts 5'! and 53 respectively, which are aligned for the selective opening or closing of an electrical circuit between the two sets of leaves. An electrical insulating bar 59 is attached between leaves 55 and rides against the nut 33 at the end of the shaft 29, so that leaves 55 are actuated by axial move-- ment of shaft 29; that is, a backward axial motion of shaft 23 moves bar 59 and leaves 55 backward, and upon lug 32 entering opening 35, the resilience of leaves 55 forces shaft 29 axially forward. Ihe free ends of resilient leaves 56 rest against yoke 45, so that they are similarly actuated by axial movement of pin M.

The two sets of leaves 55 and 5b are usually connected in series circuit between the heating units of an electric oven and the manual oven controls. The manual controls may be separate switches on the backsplash of the range or may be associated with the oven thermostat, for example. Preferably the manual controls include both a timed and a manual position, and the oven circuit is arranged so that the timer is removed from the circuit in the manual position. In the off position of the switch as shown in Fig. 5 both sets of leaves are in their most forward position, so that the electrical cir cuit between contacts 51 and 5B is open. When the timer is set for a time controlled cooking operation, as hereinbefore explained, leaves 55 and 56 are both forced backward to the position illustrated in Fig. 6. It will be noted that in this position contacts 51 and 58 remain open. When lever 38 is unlatched as previously explained, pin 44 is released for axial motion, and the resilience of leaves 56 forces the free ends of leaves 56, yoke 45, and pin 44 forward. This closes t. e eletz-- trical circuit between contacts 5i and (as shown in Fig. 4) and turns the oven on. end of the timed cooking period lug 32 enters opening 35 in rotatable plate 3%, shaft is rc-- leased for axial motion, and the resilience of leaves 55 forces bar 59 and shaft 23 for d. Yoke 45 engages plate 34, preventing further for-- ward motion of leaves 55, and consequently the electrical circuit between the contacts 5'5 and 53 is opened, thus turning the oven off.

In describing the operation of my improved time switch it will be assumed that the parts are in the position shown in Fig. 5 which is the off position of the switch. Gear 21 is rotated in a forward direction (1. e., counterclockwise) at a. fixed speed by the clock mechanism as previous-- ly explained. It will be noted that as gear 21 rotates dog 28 can pass under lever 38 so that none of the parts associated with shaft 29 interfere with rotation of gear 21. This will be referred to as the non-interfering" position of shaft 29.

Now assume that the timer is to be set for a timed cooking operation and accordingly that knob 9 has been rotated clockwise to set pointer 12 at the desired off time. Inasmuch as lug 32 is seated within opening 35 of rotatable plate 34, plate 34 is rotated in the forward direction during this operation, the final angular position of opening 35 being of course determined by the angular position of pointer l2. To set the on time knob 9 is then rotated counterclockwise until pointer 1 on disk 6 indicates the time at which the cooking operation is to begin, it being recalled that pointer 8 on disk 6 cooperates with numerals on disk I to indicate the time interval between the off and on times. Inasmuch as reverse rotation of plate 34 is prevented by ratchet means 50, counterclockwise rotation of knob 9 causes lugs 32 to rotate relative to plate 34; as lug 32 is rotated in this manner it is forced out of opening 35, thus forcing shaft 29 to move axially backward. Also it will be observed that the inner portion of lever 38 is forced into slot 3| in shaft 29 (engaging the shoulder on pin 44) during reverse rotation of shaft 29. Thus pin 44 is latched by the end portion of lever 38 and. is moved rearwardly with shaft 29 to the position shown in Fig. 6. As previously explained leaves 55 carrying contacts 51 are moved from the position shown in Fig. to the position shown in Fig. 6 by the resulting backward axial motion of shaft 29, while leaves 56 carrying contacts 53 are moved from the position shown in Fig. 5 to the position shown in Fig. 6 by backward axial motion of pin 44 and yoke 45. When the parts are in this position the timer is cooked At the and contacts 51 and 58 will remain apart only so long as the inner end of lever 38 remains in latching engagement with the shoulder of pin 44.

Now as gear 21 rotates car 28 must eventually strike the outer portion of lever 38; since there is now potential interference between car 28 and. lever 38, this axial position of shaft 29 will be referred to as the interfering position. After ear 28 reaches lever :38 further rotation of gear 21 causes car 28 to press against the outer portion of lever 38, and thus rotate lever 38 slightly counterclockwise about pivot 31. This withdraws the inner end of lever 38 at least partially from slot 3|, thereby unlatching or freeing pin 44 for axial motion, so that under the influence of resilient leaves 56 pin 44 moves forward until yoke 45 strikes plate 34. This forward motion of pin 44 starts the cooking operation by moving the contacts into the position shown in Fig. 4.

Since dog 4| permits only a slight rotation of lever 38 about pivot 31, further rotation of gear 21 carries lever 38, pivot 31, arm and shaft 29 around in a counterclockwise direction. When shaft 29 reaches its initial angular position with respect to plate 34 lug 32 re-enters opening 35, thus permitting shaft 23 to move axially forward to the off position shown in Fig. 5. Thus contacts 51 and 58 are opened, the oven heating units are de-energized, and the cooking operation is terminated. It will be observed that the interaction of yoke and plate 34 prevent further forward axial motion of pin 44 so that the shoulder of pin 44 does not extend beyond opening 3!, and thus the parts are positioned. for resetting whenever desired.

It will be understood that my invention is not limited to the specific embodiment herein illustrated and described and that the following claims are intended to cover all changes and modifications which do not depart from the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A time switch comprising a rotatable plate having an aperture therein and mounted for rotation in a. predetermined direction, means for preventing rotation of said plate in the opposite direction, an axially movable rotatable element mounted coaxially with said plate and having a lug member arranged to enter said aperture upon rotation of said element to a predetermined angular position with respect to said 1 plate, said lug having a cam surface arranged to effect disengagement of said lug and aperture upon rotation of said element in said opposite direction, spring means biasing said plate and element toward each other, means for rotating said element in said predetermined direction at a constant speed, switch means actuated by axial movement of said element, a manually rotatable setting member in driving relation with said element whereby rotation of said member in one direction effects engagement of said lug and aperture and simultaneous rotation of said element and plate, and rotation of said member in the opposite direct-ion effects disengagement of said lug and. aperture and rotation of said element alone, ,a first rotatable time indicator, means for rotating said first indicator in fixed angular relationship with respect to said element, a second rotatable time indicator, and means for rotating said second indicator in fixed angular relationship with respect to said plate.

2. A time switch comprising a rotatable plate having an aperture therein and mounted for rotation in a predetermined direction, means for preventing rotation of said plate in the opposite direction, an axially movable rotatable element mounted coaxially with said plate and having a lug member arranged to enter said aperture upon rotation of said element to a predetermined angular position with respect to said plate, said lug having a cam surface arranged to effect disengagement of said lug and aperture upon rotation of said element in said opposite direction, motor driven constant speed means engageable with said element for rotating said element in said predetermined direction, spring means biasing said plate and element toward each other,

switch means actuated by axial movement of said element, a manually rotatable setting member in driving relation with said element whereby rotation of said member in one direction effects engagement of said lug and aperture and simultaneous rotation of said element and plate, and rotation of said member in the opposite direction effects disengagement of said lug and aperture and rotation of said element alone, a first rotatable time indicator, means for rotating said first indicator in fixed angular relationship with respect to said element, a second rotatable time indicator mounted coaxially with respect to said first indicator, and means for rotating said second indicator in fixed angular relationship with respect to said plate.

3. A time switch comprising a clock mechanism including an hour indicating member and a constant speed gear having an ear extending from one of its sides, a rotatable plate having an aperture therein offset from its axis of rotation, said plate being coaxial with said gear and mounted,

for rotation in a predetermined direction, means for preventing rotation of said plate in the opposite direction, an axially movable shaft coaxial with said plate and having a lug member extending radially therefrom arranged to enter said aperture upon rotation of said shaft to a predetermined angular position with respect to said plate, said lug having a cam surface arranged to effect disengagement of said lug and aperture upon rotationof said element in said opposite direction, a radially extending arm on said shaft, said arm being positioned by axial movement of said shaft in interfering relation to said ear when said lug and aperture are disengaged and in non-interfering relation to said car when said lug is positioned in said aperture, whereby when said shaft is in the interfering position said shaft may be rotated by said constant speed member, switch means actuated by axial movement of said shaft, a manually ro-V tatable setting member in driving relation with said shaft whereby rotation of said member in one direction effects engagement of said lug and aperture and simultaneous rotation of said shaft and plate, and rotation of said member in the opposite direction effects disengagement of said lug and aperture and rotation of said element alone, a first rotatable time indicator, means for rotating said first indicator in fixed angular relationship with respect to said shaft, a second rotatable time indicator, and means for rotating said second indicator in fixed angular relationship with respect to said plate.

4. A time switch comprising a clock mechanism including a clock dial, a rotatable hour indicating member and a constant speed gear having an ear extending from one of its sides, a rotatable plate having an aperture therein offset from its axis of rotation, said plate being coaxial with said gear and mounted for rotation in a predetermined direction, means for preventing rotation of said plate in the opposite direction, an axially movable shaft coaxial with said plate and having a lug member extending radially therefrom arranged to enter said aperture upon rotation of said shaft to a predetermined angular position with respect to said plate, said lug havinga cam surface arranged to effect disengagement of said lug and aperture upon rotation of said shaft in said opposite direction, a radially extending arm on said shaft, said arm being positioned by axial movement of said shaft in interfering relation to said ear when said lug and aperture are disengaged and in non-interfering relation to said ear when said lug is positioned to said aperture, whereby when said shaft is in the interfering position said shaft may be rotated by said constant speed member, switch means actuated by axial movement of said shaft, a manually rotatable setting member in driving relation with said shaft whereby rotation of said member in one direction effects engagement of said lug and aperture and simultaneous rotation of said shaft and plate, and rotation of said member in the opposite direction effects disengagement of said lug and aperture and rotation of said element alone, first and second rotatable time indicators coaxial with the axis of rotation of said hour indicating member, means for rotating said first indicator in fixed angular relationship with respect to said shaft, and means for rotating said second indicator in fixed angular relationship with respect to said plate.

5. A time switch comprising a rotatable tripping gear having an ear extending from one of its sides, clock mechanism for rotating said tripping gear at a constant speed, a rotatable and axially movable shaft coaxial with said tripping gear, said shaft having an axial bore and also having a diametrical slot extending to the inner portion of said bore, a pin axially slidable within said bore in telescoping axial alignment with said shaft, an outwardly extending arm attached to said shaft, a pivot attached to saidarm and parallel with said shaft, a latching lever rotatably supported upon said pivot and extending generally outward from said shaft, the inner end of said lever being movable selectively to a latching position in said slot or an unlatching position substantially out of said slot and interfering when in the slot with the axial motion of said pin, an outer portion of said lever being positioned by axial movement of said shaft selectively in interfering or non-interfering relation to said ear, whereby when said shaft is in the interfering position rotation of said tripping gear brings the ear against the outer portion of the latching lever, thereby withdrawing the inner end of said lever from said slot to release'said pin for axial motion, a rotatable plate mounted coaxially with respect to said shaft, said plate having an arcuate opening therein, means for preventing reverse rotation of said plate, a lug attached to said shaft and cooperating with said plate so that said lug enters the opening in the plate in driving relation therewith thereby moving said shaft axially to the non-interfering position upon rotation of the shaft to apredetermined angular position with respect to said plate, and is forced out of the opening thereby moving said shaft axially to the interfering position upon rotation of the shaft in the reverse direction away from such angular position, a yoke atlatching lever, a first rotatable time indicator, means for rotating said first indicator in fixed angular relationship with respect to said shaft, a second rotatable time indicator, and means for rotating said second indicator in fixed angular relationship with respect to said plate.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Levenstein Nov. 10, 1925 Number 

